1. Technical Field
The present invention relates to a system and a method for motion estimation.
2. Background Art
A variety of applications and services have been increasingly available through the use of image and motion sensors. In the field of defense, for example, the modern battlegrounds tend to be aimed for counter-terrorism, anti-piracy operations, hostage rescue operations, etc., requiring the soldiers to have a real battle-like training in a virtual space for the anticipated area of operations. For this, the United States and many other advanced European countries have actively developed and implemented virtual training systems, which are on the premise that postures and behaviors of participants and trainees are reflected in real time in virtual reality.
One of the drawbacks of the conventional virtual training systems is the incapability of estimating a precise posture and position of the participant. While various poses and behaviors are recognized to a certain degree through a motion sensor or an image sensor, the traveled distance and global location of the trainee have not been accurately estimated and displayed. In the case of a military training, this not only impairs the proper calculation of quantitative training results, such as accomplishment of travel distance requirement, measurement of the amount of activity, etc., which are presented in, for example, training manuals, but also eventually makes it difficult to undertake a real battle-like training when a comprehensive combat training is carried out.
The three-dimensional posture and position of a specific object or target in a space are mostly estimated using a camera image, infrared ray or a motion sensor.
As a recently-popular low-cost solution of using a camera image, the posture is estimated based on a depth map by estimating every joint point of a human body to draw a skeleton and extracting a rotation value of the joint point based on a difference between frames of the recognized depth map. However, since the extracted rotation value of the joint point is little accurate, it is inappropriate to apply this depth map-based posture estimation method to a virtual military training system, which requires a much higher precision, although it may be applied to a general game.
In the case of capturing a motion using a motion sensor only, it may be possible to estimate the posture of a trainee by use of motion information, such as acceleration and angular velocity, obtained through acceleration and angular velocity sensors, but errors of these sensors are divergently accumulated through time, making it inappropriate for a prolonged analysis.